Structures used in construction, such as foundations and walls, include materials, such as masonry, cement, wood, plaster, stone, clay or brick that may be porous. Such porous materials are susceptible to cracking and can be degraded by water and/or loss of water from the porous materials. Below grade structures are often subjected to hydrostatic pressure from ground water. Above grade structures are subject to precipitation, moisture migration, air penetration, and water from other sources. A variety of methods and products for waterproofing and/or sealing these structures against outside water have been developed.
Moisture accumulation in a structure leads to mold growth, a significant problem in residential and commercial buildings. Buildings are often constructed with a cavity between structural walls and interior walls to trap air and moisture, which helps significantly reduce energy costs, especially for commercial buildings. The presence of excessive moisture and humidity inside the structural cavity promotes the growth of mold or mildew. Mold accumulation is the cause of two major problems. First, mold has a significant negative effect on many building materials including, but not limited to, materials used to waterproof or dampproof structures. For example, adhesives used to fasten waterproof polyvinyl sheeting to the surface of a structure can be attacked by mold and will degrade over time, eliminating the waterproofing ability of the polyvinyl sheeting. Furthermore, mold can also degrade waterproofing sealants made from tar or asphalt. These compositions contain large amounts of organic material, which is readily attacked by mold and thereby rendered ineffective as water barriers. Second, the mold in building cavities is dispersed into the building air and can cause illness and even death to the occupants of the building. Such buildings are known as “sick buildings” and this is a major health concern for commercial buildings and school buildings.
Biocides, including antimicrobial and antifungal agents, have been added to materials like paints and sealants to prevent the staining and discoloration of building surfaces caused by mold growth. However, many antimicrobial agents tend to be water soluble and can be easily leached out or washed away by rainfall. Furthermore, antimicrobial treatments applied to painted or sealed surfaces may not be effective, because the antimicrobial agent cannot diffuse through the paint or sealant to protect the underlying material. Some antimicrobial agents also cannot be applied directly to building materials because of the adverse effects of the agent on the material. For example, an antimicrobial agent added directly to cement may react with the cement and weaken it over time. Some antimicrobial agents are not properly incorporated into the matrix of building materials, and sensitive individuals can develop contact allergies from such antimicrobial agents.
Therefore, there is a need for alternative methods of preventing mold formation on structural surfaces. The ideal mold-inhibiting coating will incorporate an appropriate antimicrobial agent into its matrix, thereby allowing for adequate protection of the material while preventing harmful contact allergies to individuals. Furthermore, the ideal mold prevention coating also should act as a barrier against water or moisture to prevent further degradation of the structure, and to prevent loss of the biocidal agent by dissolution in water.